The invention relates to a cell cultivation container having a mouth portion provided with a screw cover.
In the growing of cells it is customary to use containers provided with an airtight screw cover in order to prevent contamination of the cell material and also to prevent the escape of cells or substrate to the surroundings.
However, the use of such airtight screw covers involves various practical problems. Thus, an equalization must be performed from time to time of the overpressure building up in the cultivation container, i.e. because the temperature in the container is increased from that of the surroundings to the optimum temperature of about 37.degree. C. for the cultivation of the cells. The overpressure is mainly due to the fact that the gas mixture present above the substrate tends to expand at the noted temperature increase.
In cell cultivation containers a NaHCO.sub.3 -solution is frequently used for maintaining a constant pH-value. Typically, a NaHCO.sub.3 -solution is used having a NaHCO.sub.3 -content of 0.8-3.5 g/l, preferably about 2.2 g/l. Such a buffer solution gives the desired pH-value only if a given CO.sub.2 partial pressure above the substrate is maintained, and it is therefore necessary to introduce CO.sub.2 into the cultivation container from time to time.
The equalization of the above-mentioned overpressure and the introduction of CO.sub.2 into the container are normally performed by turning the screw cover sufficiently to establish a communication between the interior of the container and a surrounding gas mixture, such as atmospheric air with an addition of 5% CO.sub.2. However, in the case of the known screw covers it is not possible to ascertain exactly when the cover has been sufficiently opened to establish such communication, yet not opened to such an extent that material may unintentionally escape from the container, or contaminating matter, including micro-organisms, may penetrate into the container.